Update Changelog/test for comment after DOCTYPE

Changelog.md

@@ -17,6 +17,11 @@
 
 ### Bug Fixes
 
+- [#603]: Make it possible to include an XML comment between a <!DOCTYPE> and
+  the root element in the file.
+
+[#603]: https://github.com/tafia/quick-xml/pull/603
+
 ### Misc Changes
 
 [#601]: https://github.com/tafia/quick-xml/pull/601

src/de/mod.rs

@@ -2880,6 +2880,8 @@ impl StartTrimmer {
     #[inline(always)]
     fn trim<'a>(&mut self, event: Event<'a>) -> Option<PayloadEvent<'a>> {
         let (event, trim_next_event) = match event {
+            // Trim CData/Text events after DOCTYPE so next event encountered
+            // by deserializer will be a Start event (allowing Struct parser to suceed)
             Event::DocType(e) => (PayloadEvent::DocType(e), true),
             Event::Start(e) => (PayloadEvent::Start(e), true),
             Event::End(e) => (PayloadEvent::End(e), true),
@@ -4450,4 +4452,24 @@ mod tests {
             }
         }
     }
+
+    #[test]
+    fn allow_comments_between_doctype_and_root_element() {
+        let mut de = Deserializer::from_str(r#"
+        <!DOCTYPE dict>
+        <!-- comment between doctype and root element -->
+        <!-- another comment -->
+        <doc>
+        </doc>
+        "#);
+        assert_eq!(
+            de.next().unwrap(),
+            DeEvent::Start(BytesStart::new("doc"))
+        );
+        assert_eq!(
+            de.next().unwrap(),
+            DeEvent::End(BytesEnd::new("doc"))
+        );
+        assert_eq!(de.next().unwrap(), DeEvent::Eof);
+    }
 }